Investigating the Prevalence of Mycobacterium Avium Subspecies Paratuberculosis (MAP) in Industrial Dairy herds using Ziehl-Neelsen Staining, Culture, and PCR in Mashhad, Iran

Mycobacterium avium subspecies paratuberculosis (MAP) is the causative agent of Johne's disease in wild and domestic ruminants. Clinically, infected cattle show emaciation symptoms, diarrhea, and death. Asymptomatic subclinical cases can intermittently shed MAP through feces and milk and infect other cattle animals, thus increasing the risk of infection. The purpose of the present study was to detect the prevalence of this disease in dairy cattle. For this purpose, 348 samples were randomly collected from 15 cattle farms. All fecal samples were subjected to ZN staining and PCR of nucleotide sequences related to specific MAP gene fragments (IS900, F57) and were cultured in Harold's egg yolk culture medium after being disinfected with solution (0.0% HPC75). PCR testing of 116 fecal samples (33.3%, CI:95% 28.3-38.2), ZN staining of 23 samples (6.6%, CI: 95% 4-9.2), and fecal sample culture of only 15 samples (4.3%, CI:95% 2.3-6.3,) were infected with MAP. Comparison of test results showed poor agreement (kappa statistic: 0.19) between ZN staining and PCR results and poor agreement (kappa statistic: 0.13) between PCR test and fecal culture. This study highlights the advantages of PCR for detecting MAP in subclinically infected cattle compared to ZN staining and fecal culture. Therefore, it can be used for early detection and control of MAP in cattle and at-risk populations.